Freshwater pollution

What is water pollution? …the introduction of chemical, physical, or biological agents into water that degrades the quality of the water and affects the organisms that depend on it.

Where can polluted water be found? EVERYWHERE…mostly in areas where water treatment is not available (undeveloped countries) or in countries that do not have anti-pollution laws.

2 main causes of water pollution 1)Industrialization 2)Large human population

2 categories of water pollution 1) point pollution 2) nonpoint pollution

Point pollution …is pollution discharged from a single source. Ex: factory, sewage treatment plant Easy to identify where the pollution is coming from.

Nonpoint pollution …pollution that comes many sources. Ex: storm water drains, highways/roadways Difficult to identify to source of pollution Nonpoint pollution is the most common category of water pollution.

Wastewater treatment Wastewater is a source of pollution, it is the water that is drained from homes & businesses. Most wastewater is mostly biodegradable & easy to treat.

How a treatment plant works 1)Raw sewage is run through a screen to remove large particles. 2) The material is left to settle in a settling tank.

3) Aeration tank - Water and air is mixed with the sewage (sludge). The lighter material is pumped off to another settling tank. The heavier sludge is sent to a tank for the material to break down further. (The material sent to break down will go through the aeration tank again later.)

4) The material in the 2 nd settling tank is then sent to the chlorination tank. Chlorine & other chemicals are added to disinfect the water.

Sometimes partially treated waste is sent into rivers or lakes to complete a natural biodegrading process.

The harmful effects of water pollution 1)Many types of pollution include the growth of waterborne pathogens (disease causing agents or organisms). *cause diseases and death if ingested.

2) Biological magnification – toxins build up in organisms in a food chain / web. As an organism eats other organisms, the poisons accumulate in their system over time. EX: DDT

3) Artificial Eutrophication – the accumulation of nutrients that causes a lake or other body of water to “fill in”. * Mainly caused by phosphorous or nitrogen being added to the water. (detergents& fertilizers) * cause die off in the water.

4) Thermal pollution – increase in temperature of a body of water. * usually the result of factories or industry that uses the water to cool equipment. * can cause fish kills and low oxygen in the water

Groundwater pollution Caused by land pollution seeping into aquifers. Can not be cleaned & will be polluted for a long time.

US laws regulating water quality 1) 1972 Clean Water Act – clean surface water, eliminate pollution discharge into water ways, removal of metals from watewater.

2) 1972 Marine Protection, Research, & Sanctuaries Act – control the dumping of sewage & toxins into oceans.

3) 1980 Comprehensive Environmental Response Compensation & Liability Act- “The Superfund Act” – makes polluters clean up the waste or pay for the clean up.